Method and apparatus for forming a uniform layer of powder developer on a surface

ABSTRACT

In an electrostatic recording system in which a donor roller is employed to carry a layer of toner to the photo-receptor member for use in developing an electrostatic latent image, the donor roller is loaded with a uniform layer of toner by rotating the donor roller through a bath of toner in a vibrating pan. The donor roller is positioned so that a portion of its circumference passes through the toner in the vibrating pan forming a varying depth bath of toner, the thinnest depth of toner being sufficiently thin to fluidize the toner in this thin layer area. In this thin level of toner the vibrations of the vibrating pan drives the toner into a highly fluid state and the toner adheres to the surface of the donor roller thereby loading the roller with a layer of toner. The layer is wiped to a uniform thickness as the roller passes through thicker levels of toner in the toner bath which are not in a fluid state.

United States Patent Maksymiak et al.

[54] METHOD AND APPARATUS FOR FORMING A UNIFORM LAYER OF POWDER DEVELOPER ON A SURFACE [72] Inventors: John Maksymiak, Penfield; Lawrence M. Hart, Ontario, both of N.Y.

[73] Assignee: Xerox Corporation, Stamford,

Conn.

22] Filed: Jan. 6, 1971 21 Appl. No.: 104,364

[451 Nov. 21, 1972 3,203,394 8/1965 Hope et a1. ..118/637 Primary Examiner-Mervin Stein Assistant Examiner-Leo Millstein Attorney-James J. Ralabate, Donald F. Daley and Kenneth E. Merklen [57] ABSTRACT In an electrostatic recording system in which a donor roller is employed to carry a layer of toner to the photo-receptor member for use in developing an electrostatic latent image, the donor roller is loaded with a uniform layer of toner by rotating the donor roller through a bath of toner in a vibrating pan. The donor roller is positioned so that a portion of its circumference passes through the toner in the vibrating pan forming a varying depth bath of toner, the thinnest depth of toner being sufficiently thin to fluidize the toner in this thin layer area. In this thin level of toner the vibrations of the vibrating pan drives the toner into a highly fluid state and the toner adheres to the surface of the donor roller thereby loading the roller with a layer of toner. The layer is wiped to a uniform thickness as the roller passes through thicker levels of toner in the toner bath which are not in a fluid state.

11 Claims, 2 Drawing Figures V PATENIEDHUVZI 1m SHEET 1 OF 2 INVENTORS, JOHN MAKSYMIAK LAWRENCE M. HART ATTORNEY METHOD AND APPARATUS FOR FORMING A UNIFORM LAYER OF POWDER DEVELOPER ON A SURFACE The present invention relates to the art of electrostatic recording and in particular to methods and apparatus for providing a uniform layer of material for developing a latent image into a visible image such as toner, for example, on a toner donor member.

In the art of electrostatic recording, especially in xerography, it is usual to form an-electrostatic charge pattern, corresponding to the information to be recorded, on a photoconductor or photoreceptor member. This is sometimes accomplished by substantially uniformly charging the photoconductor member by use of a corona discharge wire, for example, and dissipating the charge in pattern configuration by exposure of the photoconductor member to a pattern of light. The light striking of the charged area of the photoconductor portions dissipates the charge and an invisible electrostatic charge pattern remains on the photoconductor member. This is sometimes referred to as a latent image. The latent image may be developed into a visible image by providing an attractable material, such as a visible powder, dust, mist or the like having tonal characteristics and by making such material available for attraction to the photoconductor member in those areas where the charge pattern has been retained.

In this manner the latent image on the photoconductor member may be developed into a visible image. The visible image may then be transferred for more permanent retension, onto a recording medium, such as paper, for example.

The visible image formed by the pattern of the developer on the photoconductor member may be transferred to the recording medium by creating an electrostatic charge of sufficient strength and proper polarity so as to attract the developer from the photoconductor member to the recording medium and thereafter fixing or permanentizing the powder material onto the recording medium.

When the electrostatic charge pattern of the latent image is very small and/or finely detailed, the visible powder material used for developing the latent image into a visible image must be correspondingly fine and/or small and uniformly applied to the latent image to provide clear, sharp visible characters.

This visible powder material may be in several different forms but preferably a solid form of fine powder, for example, finely powdered color material, such as pigmented or dyed resins, plastics and the like, may be used. Desirably, the powder may be powdered resin materials, preferable thermoplastic, colored with various color pigment or carbon black such as disclosed in U.S. Pat. Nos. 2,638,416 and 2,659,607, for example. Such material is herein referred to as toner.

There are several ways of applying the fine toner to a latent image to provide tonal characteristics for creation of the image. U.S. Pat. No. 3,008,826 discloses methods and apparatus for applying toner directly to the photoconductor material and directly to the recording medium. U.S. Pat. No. 3,405,682 discloses the use of an intermediate or donor member which first picks up the toner from a reserve or sump and presents the toner to the photoconductor member. Since the intermediate member effectively donates the toner to the photoconductor member, this intermediate member will be referred to as the donor component.

The use of a donor component has the advantage of providing a ready made uniform carpet, coating or layer of powder developer to the photoconductive member and the photoconductor member can then take from this uniform coating or layer of toner that which the electrostatic charges on the photoconductor require to convert the latent image to a visible image.

However, if the coating or layer of toner on the donor member is mechanically and/or electrically nonuniform and/or contains lumps and/or agglomerates, transfer of the toner between the donor and the photoconductor members will be blotchy, non-uniform and uneven to the extent that the visible pattern of the latent image will be corrupted.

Thus it will be seen that when employing the donor technique of transferring toner to a photoconductor it is desirable that the coating or layer of toner on the donor member be as uniform and even as possible and free from lumps, build-up, and/or agglomerates and bare space.

The present invention provides a novel method and apparatus which ensures the coating or layer of donatable toner applied to a donor material is uniform, even and free from toner build-up, lumps and agglomerates.

It is therefore an object of the invention to provide a donor member in an electrostatic recording system on which a uniform, even and agglomerate free coating or layer of toner is generated, which uniform, even and agglomerate free coating or layer is transferred to a photoreceptor.

Another object is to provide a novel donor roller toner loading system in which the surface of the donor roller is progressively cleaned by passing the surface through a bath of inactive toner, then loaded by passing the cleaned surface through a bath of active toner, vibrating under controlled conditions and thereafter passing the loaded surface of the donor roller through a bath of inactive toner for smoothing out the coating or layer of toner for providing a uniform, even and agglomerate free coating or layer of toner.

These and other objects will become apparent from a reading of the following detailed description with reference to the drawings in which:

FIG. 1 is a simplified diagram of an electrostatic recording system employing a donor roller and,

FIG. 2 is a more detailed view of the donor roller and vibrating toner pan.

Referring in more detail to FIG. 1, the simplified diagram of an electrostatic recording system is presented as a xerographic system in which a donor roller 10 is loaded with a coating or layer of toner 31 and makes available or donates such toner to a photoreceptor drum l2.

Briefly, the photoreceptor drum 12 is of the conventional type used in xerographic recording devices and has the surface thereof cleaned as represented by the cleaning brush 13 driven by a means, not shown. A tray or retainer 14 is shown for holding the material removed or cleaned from the surface of the drum.

The drum 12 is rotated as by the motor 15 and drive belt 16 in a clockwise direction. As the surface of the drum passes the corona discharging device 17 an electrostatic charge is placed on the surface of the photoreceptor. The charge is preferably uniform across the surface of the photoreceptor drum T2 and is here indicated as a positive charge, as indicated by the plus in a circle, representing the positive terminal of a direct current source, which is the driving potential for the corona discharge device 117. As the drum 112 is rotated the surface is illuminated in a pattern, imaging the document source 2t]? via an optical and illuminating system represented by a lamp 121, lenses 22 and 23, and mirror 24. The document 2b is moved past the illuminating area 2%, as represented by the arrow 26 and the detail or pattern of the to-be-recorded instrument 241i is imaged on the charged surface of the rotating photoreceptor 12, leaving a latent image on the surface of the drum T2 in the form of charge differential.

This process follows the principles taught in the Carlson US. Pat. No. 2,297,691, issued Oct. 6, 1942 for the creation of a latent image on a photoconductive layer.

The latent image on drum T2 may now be developed into a visible image by applying suitable marking particles such as toner to the surface of the photoreceptor i2 carrying the latent image. The toner may be applied to, or made available to the photoreceptor 12 by use of a donor such as taught by Mayo in his US. Pat. No. 2,895,847.

The presentation in FIG. ll represents a donor roller lb which may be of the type described by Hope et al. in US. Pat. No. 3,203,394 is issued Aug. 31, 1965. The roller lift is more clearly illustrated in MG. 2 where the laminations are shown in more detail including a metal grid 27 (particularly illustrated in the separated section of MG. 12) an insulated layer 2% and a conductor layer 29. The metal (preferably copper) grid 27 in the surface of the donor roller Ml is charged with a positive DC potential dd so as to generate an electrostatic field.

As will be more fully described below the donor roller lid is loaded with a coating or layer of toner Bill which is presented to the photoreceptor drum 112 at a point or area of contact 35. The area of contact" 35 may in fact be an area or point of physical contact where the donor roller and the photoreceptor drum are physically touching or the area of contact 35 may be an area or point where the donor roller and the photoreceptor drum are physically separated but are sufficiently close so that toner may transfer from the donor roller to the photoreceptor drum. The toner on the surface of the donor roller had previously been charged, as by use of a corotron 32, negatively and therefore portions of the toner Elli on the donor roller lib are attracted to the positive electrostatic charges on the photoreceptor l2, thus converting the latent image into a visible image on the surface of the photoreceptor drum. This is indicated at dtlia on the drum 12. Although the drum l2 and roller llti are illustrated as substantially the same diameter this is not necessary and the diameter of the two components may be similar or dissimilar, as described.

A support material as is brought into contact with the surface of the photoreceptor drum and the visible (toner) image is transferred to the support material 36 by help of a corona discharge device It? which applies a high positive corona charge on the support material 3%, for example, paper. The visible image on the support material at Eltl, for example, is fixed or fused to the support material by any one of several known methods,

here a source of heat 4% is used to apply a fusing heat to the toner on the support material.

As is well known to one skilled in the art, the rotation of the drum i2, movement or advance of the document 2b to be recorded and movement or advance of the support material 36 are all synchronized so that the image of copy at 3d of the document 20 may be at a magnification as determined by the optical system 22/24/23. The photoreceptor drum T2 and the donor roller MD are driven in opposite directions, as indicated by the clockwise direction arrow 41 and the counterclockwise direction arrow 42. This may be readily accomplished by use of proper gearing on the drive motor ilb'.

Referring now to FIG 2, the donor roller W is illustrated laminated as aforementioned. It will be noticed in lFllG. ii and in FIG. 2 that during transfer of toner from the donor roller Mi surface to photoreceptor drum 112 surface only part of the layer of toner 31 is transferred. Those portions transferred are particularly pointed out at 1349a. The portions of toner remaining on the donor roller lltl are represented at Ma.

Preferably the surface of the donor roller ll) is cleaned and a new layer or coating of toner is applied to the roller application to the photoreceptor or photoconductor drum 112. The positive DC potential 30 is applied to the grid 27, thereby creating a positive charge on the entire grid surface of the donor drum.

in order to assist in cleaning the donor roller surface any charge on the toner is removed or dissipated by applying an alternating current charge by a corona discharge device such as represented at 43.

With the toner in a neutral charge condition attraction by the charged condition of the surface of the donor roller 12 is minimal and the toner may easily be removed from the surface of the roller.

in accordance with the invention there is provided a vibrating plate or dish 45. Vibrations applied to the plate or dish 45 are generated in the vibration generator represented by 4b.

lit will be appreciated that pulverized materials, having fine, powder-like characteristics normally have a damping effect on transmission of vibration. The toner 311 is a fine powder with such damping effect on the transmission of vibration.

The vibrating pan or plate 45 is so constructed and positioned, with respect to the circumferential surface of roller it]; that the toner 311 in the pan 45 forms a bath of varying thickness or depth, the lowest point of the circumference of the roller lid being somewhat less than one-eighth of an inch from the surface of the pan 45. Thus, the toner bath dll will range in depth from less than one-eighth of an inch to a depth substantially more than one-eighth of an inch, depending upon the contour of the roller and the amount of toner in the pan 45.

Preferably the area of the circumference of the roller it]? enveloped in the toner bath forms a bath of varying depth, with respect to the surface of the pan 45. The depth may range from very thin, for example, less than one-eighth of an inch to 1 inch or more depending on the amount of toner in the pan. The varying depth of toner may be divided into three general areas, such as indicated by the brackets 5d, fill, and 52 in FlG 2. Bracket Sill indicates an area here referred to as the active area of toner 31. Toner in this area is sufficiently shallow in depth to be converted into a fluid" state by the vibrations of the vibrating pan 45. it has been found that the degree of fluidization of the toner in the active area is inverseiy proportional to the depth of the toner and the amount of agglomerates deposited on the toner layer formed on the surface of the roller W is directly proportional to the depth of the toner. In other words, the narrower the distance between the surface of the vibrating plate and the surface of the circumference of the roller, the thinner the layer of toner between the two surfaces and more influenced the toner is in such thin layer by the vibrations of the vibrating pan. The more influenced the toner is, the more fluid the toner becomes and, the more fluid the toner becomes the smoother the layer of toner deposited on the surface of the roller.

The area on either side of the active area Silt, indicated by the brackets Sll and 52 are here referred to as inactive areas. In these areas the amount of vibration transmitted through the toner 31 from the surface of the vibrating pan 435 is insufficient to drive the toner to a fluid state sufficient to load the surface of the roller with a smooth layer of toner. However, it has been found that an area of inactive toner, such as indicated as 511 is useful in wiping toner, such as 311a, from the surface of the roller llti so as to clean the surface of roller llil before that portion of the surface enters the active area. in order to aid in the wiping, cleaning action a toner charge neutralizing corona discharge device 43 is provided. The corona discharge device 43 generates an alternating current charge which neutralizes the charged condition of the toner 31a and as the roller w enters the inactive toner area 51 the toner 3i wipes the toner 311a from the surface of the drum by frictional contact with the toner in the inactive area. The surface of the roller 1141) will progressively pass into the active area 5th where the toner is in a fluid state. Toner in such a fluid state is charged through triboelectrification and will adhere to the surface of the donor roller lift. in addition, as stated above, the grid 27 on the surface of the roller member is charged by the fringe fields formed by the grid and drum and the electrostatic field thereby created attracts both positively charged and negatively charged toner 31 supported in the vibrating pan 45. Especially attracted is the toner in the active area 50 since this toner is in a fluid state and toner to toner cohesion is minimized. As the roller surface then proceeds to pass through the inactive or substantially less active area 52, the layer of toner adhering to the surface of the roller will become uniformly thinned out by the frictional contact with the toner in the inactive or less active area 52. The uniform thinning of the layer of adhering toner is accomplished by removing weakly adhering toner particles by the abrasive action of the toner in the inactive area 52. Thus a layer or coating of toner 311 of uniform and even thickness is obtained on the donor roller for transfer to a photoreceptor drum.

it has further been found the vibrating pan or plate 45 may be vibrated at any angle which drives the toner toward the donor roller. That is to say, some angles of vibration will tend to drive toner to the sides of the plate, such angles are unsatisfactory since this will cause a void between the surface of the vibrating pan 45 and the surface of the donor roller 10. Essentially, a highly effective range of angle of vibration which maintains toner in contact with the surface of the roller and generates the preferred active area is a vibration angle of about 30 to 35 to the horizontal. As shown in FIG. 2, the range of angle of vibration is not necessarily limited to such range since such range may be expanded.

Thus there has been described a method and apparatus for loading a smooth, uniform layer of toner on the surface of a donor roller member in an electrostatic recording device in which there has been disclosed a working embodiment with a range of values given for vibrating angle and toner depth, for example. It should be clearly understood the ranges of values given should not be construed as limiting, as such range of values may be expanded, as will be familiar to those skilled in the art. Other changes and substitutions of parts and structure may be made as will be obvious to those skilled in the art, without departing from the spirit of the invention as defined in the claims.

WHAT IS CLAHVIED IS:

1. An electrostatic recording apparatus having means to develop an electrostatic latent image on an electrostatic latent image bearing surface in which the developing means includes a supply of toner for developing the latent image into a visible image and a donor member having a toner surface for supplying a quantity of said toner to the electrostatic latent image bearing surface inthe form of a smooth uniform layer of toner, an improved means for loading the toner surface of the donor member with a uniform layer of toner for presentation to the latent image bearing surface, the improvement comprising;

a pan for supporting a supply of toner for forming a toner bath,

means supporting said donor member in said toner bath for forming toner areas of varying thickness including a thin area of active toner and a thicker area of inactive toner,

means for vibrating at least the surface of said pan supporting said toner for driving said toner in said thin active toner area into a fluid state sufficient for loading toner in a smooth layer onto the donor member surface and for driving said toner in thicker inactive areas into a state insufficient for loading toner onto the donor member toner surface in a smooth layer and means for moving said donor member toner surface through said active and inactive areas of said toner bath for loading toner onto the toner surface.

2. The apparatus of claim 1 wherein said means supporting said donor member forms an active area of toner with an inactive area of toner on each side of the active area.

3. The apparatus of claim 2 wherein said means for moving the donor member toner surface moves the toner surface through one inactive area of toner for cleaning the toner surface with the toner in the inactive area, then through the active toner area for loading the toner surface with toner in the fluid state and then through the other inactive toner area for forming a layer of toner having uniform thickness.

4. An electrostatic recording apparatus having meansto develop an electrostatic latent image on an electrostatic latent image bearing surface in which the developing means includes a supply of toner for developing the latent image into a visible image and a donor roller for supplying a quantity of said toner to the electrostatic latent image bearing surface in the form of a smooth uniform layer of toner, an improved means for loading the donor roller with a uniform layer of toner for presentation to the latent image bearing surface, the improvement comprising;

a pan for supporting a quantity of toner for forming a toner bath,

means for vibrating at least the surface of said pan at an angle sufficient for driving said toner to fill in voids in the toner for maintaining constant contact with the entire surface of the roller submerged in the toner bath and for driving toner in a sufficiently narrow layer, between a portion of the surface of the roller and said vibrating surface into a fluid state,

means supporting said donor roller in said toner bath for forming varying depths of the toner in the toner bath with respect to the said surface of said pan for forming a layer in said pan sufficiently narrow in depth for being driven into a fluid state by the vibrations of said vibrating surface and means for rotating said roller through said toner bath and through said layer of toner driven into a fluid state for loading said surface of said roller with toner for forming a layer of toner on the surface of said donor roller.

5. An electrostatic recording apparatus having means to develop an electrostatic latent image on an electrostatic latent image bearing surface in which the developing means includes a supply of toner for developing the latent image into a visible image and a donor roller for supplying a quantity of said toner to the electrostatic latent image bearing surface an improved means for loading the donor roller with a uniform layer of toner for presentation to the latent image bearing surface, the improvement comprising;

a pan for supporting a quantity of toner therein,

means for vibrating at least the surface of said pan so supporting said toner,

support means for supporting said donor roller so that at least a portion of the circumference of said donor roller is submerged in the toner at least less than one-eighth of an inch from the surface of said pan and means for rotating said roller for passing the circumference of said roller through said powder developer.

s. An electrostatic recording apparatus as in claim d and in which said vibrating means vibrates the surface of said pan at an angle of 30 to 35 from the horizontal.

7. An electrostatic recording apparatus having means for developing an electrostatic image on the surface of an electrostatic image bearing drum in which toner particles are supplied to the surface of the electrostatic image bearing drum by a donor roller improved means for loading toner particles onto the surface of the donor roller for supplying toner particles in a uniform layer to the electrostatic image bearing drum, the improvement comprising,

means for supporting said image bearing drum for rotating said drum by a drive means,

means for supporting said donor roller for rotating said roller by a drive means, said drum and said roller positioned so that a portion of each of their respective surfaces are in contact,

drive means for driving said drum and said roller in opposite directions respectively,

pan means having a surface and sides for supporting a quantity of toner particles, said pan means positioned so that at least a portion of the periphery of said roller extends into said pan means for varying the thickness of the layer of toner particles supported in said means, the thickness of said layer varying from less than one-eighth of an inch to more than one-eighth of an inch thick, and

means for vibrating the surface of said pan means at an angle sufficient to make fluid a portion of the layer of toner particles which has a thickness of substantially one-eighth of an inch or less.

it. An electrostatic recording apparatus as in claim 2 and in which said vibrating means vibrates the surface of said pan means at an angle of 30 to 35 from the horizontal.

9. An electrostatic recording apparatus having means to develop an electrostatic latent image on an electrostatic latent image bearing surface in which the developing means includes a supply of toner for developing the latent image into a visible image and a donor roller for supplying a quantity of said toner to the electrostatic latent image bearing surface in the form of a smooth uniform layer of toner, an improved means for loading the donor roller with a uniform layer of toner for presentation to the latent image bearing surface, the improvement comprising;

a pan for supporting a supply of toner for forming a toner bath,

means for vibrating at least the surface of said pan so supporting said toner for driving said toner to fill in voids in the toner between said pan and said donor roller and for driving the toner in a predetermined area into a fluid state, said predetermined area in said bath at toner ranging in depth from substantially one-eighth of an inch to substantially less than one-eighth of an inch,

means for supporting said donor roller so that at least a portion of the circumference of said roller is submerged in said toner and sufficiently close to the surface of said pan for forming said predetermined area in which said toner is driven into a fluid state upon being vibrated and means for rotating said roller for passing the surface of said roller through the toner bath.

lltlll. An electrostatic recording apparatus having means to develop an electrostatic latent image on an electrostatic latent image bearing surface in which the developing means includes a supply of toner for developing the latent image into a visible image and a donor roller for supplying a quantity of said toner to the electrostatic latent image bearing surface in the form of a smooth uniform layer of toner, an improved means for loading the donor roller with a uniform layer of toner for presentation to the latent image bearing surface, the improvement comprising;

a pan for supporting a supply of toner for forming a toner bath,

means for vibrating at least the surface of said pan supporting the toner for driving the toner to fill in surface of the pan so that upon vibrating the pan, the toner between the roller and pan is driven into a fluid state and means for rotating the roller for passing the surface of the roller through the toner bath.

11. An electrostatic recording apparatus as in claim 10 and in which said means for vibrating vibrates said surface of said pan at an angle substantially within the range of 30 to 35 from the horizontal. 

1. An electrostatic recording apparatus having means to develop an electrostatic latent image on an electrostatic latent image bearing surface in which the developing means includes a supply of toner for developing the latent image into a visible image and a donor member havinG a toner surface for supplying a quantity of said toner to the electrostatic latent image bearing surface in the form of a smooth uniform layer of toner, an improved means for loading the toner surface of the donor member with a uniform layer of toner for presentation to the latent image bearing surface, the improvement comprising; a pan for supporting a supply of toner for forming a toner bath, means supporting said donor member in said toner bath for forming toner areas of varying thickness including a thin area of active toner and a thicker area of inactive toner, means for vibrating at least the surface of said pan supporting said toner for driving said toner in said thin active toner area into a fluid state sufficient for loading toner in a smooth layer onto the donor member surface and for driving said toner in thicker inactive areas into a state insufficient for loading toner onto the donor member toner surface in a smooth layer and means for moving said donor member toner surface through said active and inactive areas of said toner bath for loading toner onto the toner surface.
 1. An electrostatic recording apparatus having means to develop an electrostatic latent image on an electrostatic latent image bearing surface in which the developing means includes a supply of toner for developing the latent image into a visible image and a donor member havinG a toner surface for supplying a quantity of said toner to the electrostatic latent image bearing surface in the form of a smooth uniform layer of toner, an improved means for loading the toner surface of the donor member with a uniform layer of toner for presentation to the latent image bearing surface, the improvement comprising; a pan for supporting a supply of toner for forming a toner bath, means supporting said donor member in said toner bath for forming toner areas of varying thickness including a thin area of active toner and a thicker area of inactive toner, means for vibrating at least the surface of said pan supporting said toner for driving said toner in said thin active toner area into a fluid state sufficient for loading toner in a smooth layer onto the donor member surface and for driving said toner in thicker inactive areas into a state insufficient for loading toner onto the donor member toner surface in a smooth layer and means for moving said donor member toner surface through said active and inactive areas of said toner bath for loading toner onto the toner surface.
 2. The apparatus of claim 1 wherein said means supporting said donor member forms an active area of toner with an inactive area of toner on each side of the active area.
 3. The apparatus of claim 2 wherein said means for moving the donor member toner surface moves the toner surface through one inactive area of toner for cleaning the toner surface with the toner in the inactive area, then through the active toner area for loading the toner surface with toner in the fluid state and then through the other inactive toner area for forming a layer of toner having uniform thickness.
 4. An electrostatic recording apparatus having means to develop an electrostatic latent image on an electrostatic latent image bearing surface in which the developing means includes a supply of toner for developing the latent image into a visible image and a donor roller for supplying a quantity of said toner to the electrostatic latent image bearing surface in the form of a smooth uniform layer of toner, an improved means for loading the donor roller with a uniform layer of toner for presentation to the latent image bearing surface, the improvement comprising; a pan for supporting a quantity of toner for forming a toner bath, means for vibrating at least the surface of said pan at an angle sufficient for driving said toner to fill in voids in the toner for maintaining constant contact with the entire surface of the roller submerged in the toner bath and for driving toner in a sufficiently narrow layer, between a portion of the surface of the roller and said vibrating surface into a fluid state, means supporting said donor roller in said toner bath for forming varying depths of the toner in the toner bath with respect to the said surface of said pan for forming a layer in said pan sufficiently narrow in depth for being driven into a fluid state by the vibrations of said vibrating surface and means for rotating said roller through said toner bath and through said layer of toner driven into a fluid state for loading said surface of said roller with toner for forming a layer of toner on the surface of said donor roller.
 5. An electrostatic recording apparatus having means to develop an electrostatic latent image on an electrostatic latent image bearing surface in which the developing means includes a supply of toner for developing the latent image into a visible image and a donor roller for supplying a quantity of said toner to the electrostatic latent image bearing surface an improved means for loading the donor roller with a uniform layer of toner for presentation to the latent image bearing surface, the improvement comprising; a pan for supporting a quantity of toner therein, means for vibrating at least the surface of said pan so supporting said toner, support means for supporting said donor roller so that at least a portion of the circumference of said Donor roller is submerged in the toner at least less than one-eighth of an inch from the surface of said pan and means for rotating said roller for passing the circumference of said roller through said powder developer.
 6. An electrostatic recording apparatus as in claim 5 and in which said vibrating means vibrates the surface of said pan at an angle of 30* to 35* from the horizontal.
 7. An electrostatic recording apparatus having means for developing an electrostatic image on the surface of an electrostatic image bearing drum in which toner particles are supplied to the surface of the electrostatic image bearing drum by a donor roller improved means for loading toner particles onto the surface of the donor roller for supplying toner particles in a uniform layer to the electrostatic image bearing drum, the improvement comprising, means for supporting said image bearing drum for rotating said drum by a drive means, means for supporting said donor roller for rotating said roller by a drive means, said drum and said roller positioned so that a portion of each of their respective surfaces are in contact, drive means for driving said drum and said roller in opposite directions respectively, pan means having a surface and sides for supporting a quantity of toner particles, said pan means positioned so that at least a portion of the periphery of said roller extends into said pan means for varying the thickness of the layer of toner particles supported in said means, the thickness of said layer varying from less than one-eighth of an inch to more than one-eighth of an inch thick, and means for vibrating the surface of said pan means at an angle sufficient to make fluid a portion of the layer of toner particles which has a thickness of substantially one-eighth of an inch or less.
 8. An electrostatic recording apparatus as in claim 2 and in which said vibrating means vibrates the surface of said pan means at an angle of 30* to 35* from the horizontal.
 9. An electrostatic recording apparatus having means to develop an electrostatic latent image on an electrostatic latent image bearing surface in which the developing means includes a supply of toner for developing the latent image into a visible image and a donor roller for supplying a quantity of said toner to the electrostatic latent image bearing surface in the form of a smooth uniform layer of toner, an improved means for loading the donor roller with a uniform layer of toner for presentation to the latent image bearing surface, the improvement comprising; a pan for supporting a supply of toner for forming a toner bath, means for vibrating at least the surface of said pan so supporting said toner for driving said toner to fill in voids in the toner between said pan and said donor roller and for driving the toner in a predetermined area into a fluid state, said predetermined area in said bath at toner ranging in depth from substantially one-eighth of an inch to substantially less than one-eighth of an inch, means for supporting said donor roller so that at least a portion of the circumference of said roller is submerged in said toner and sufficiently close to the surface of said pan for forming said predetermined area in which said toner is driven into a fluid state upon being vibrated and means for rotating said roller for passing the surface of said roller through the toner bath.
 10. An electrostatic recording apparatus having means to develop an electrostatic latent image on an electrostatic latent image bearing surface in which the developing means includes a supply of toner for developing the latent image into a visible image and a donor roller for supplying a quantity of said toner to the electrostatic latent image bearing surface in the form of a smooth uniform layer of toner, an improved means for loading the donor roller with a uniform layer of toner for presentation to the latent image bearing surface, the improVement comprising; a pan for supporting a supply of toner for forming a toner bath, means for vibrating at least the surface of said pan supporting the toner for driving the toner to fill in voids in the toner between the pan and the donor roller and for driving the toner in the thinnest area between the roller and pan into a fluid state sufficient for loading toner in a smooth layer onto the roller while driving toner in the thicker areas between the roller and pan into a state insufficient for loading toner in a smooth layer onto the roller, means for supporting the donor so that at least a portion of the circumference of the roller is submerged in the toner and is sufficiently close to the surface of the pan so that upon vibrating the pan, the toner between the roller and pan is driven into a fluid state and means for rotating the roller for passing the surface of the roller through the toner bath. 